Ultraviolet (UV) liquid disinfection systems have been long known, utilizing UV light to inactivate microorganisms. Higher inactivation levels are achieved with higher UV dose values. Light Emitting Diodes (LED's) are well known for having a high luminous efficiency and for being highly-reliable light sources. LED modules or LED chips are also known for their high switching rates, meaning that a LED module may be instantly lightened and instantly turned off. Each LED element includes a module (i.e. a chip or a die) of semiconductor wafer doped to form a plurality of diodes designed to emit light when electrically powered. The wavelength in which light is emitted from a LED depends on the semiconductor crystal included in the LED module. Various LED modules may emit light at wavelengths from the infrared to the ultraviolet (200 nm-850 nm). UV LED modules are mercury-free, which makes them suitable for treating drinking water.
Since most LED modules have low lightening intensity and require a low amount of energy relative to other light sources, such as medium pressure UV lamps, it would be beneficial to use as many modules as possible in a single lightening device. LED modules for example, in the range of the UV germicidal spectrum (200-320 nm), are usually grouped together in the form of a LED array. Previous attempts to disinfect water using LED as a light source were only partially successful. Commercial UV LED-based disinfection systems are limited to disinfecting small amounts of water, due to the limited lightening intensity of the LED modules.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.